flagellum
Enable an agent to recognise a flagellum, assess its attachment, integrity and activity, and judge which observations or interventions are appropriate in its cellular context.
Research draft, second pass
A second pass drafted this model: the structure a model of this thing needs, and what is known about it in the world. The line under this one says how the second half was obtained - researched against sources, or recalled without web access, in which case nothing here was read anywhere and every claim is a lead to verify. Unreviewed either way.
Researched by: Codex + Grok
Purpose and description
Enable an agent to recognise a flagellum, assess its attachment, integrity and activity, and judge which observations or interventions are appropriate in its cellular context.
A flagellum is a long, thin motility organelle that propels a cell either by rotation of an extracellular protein filament (Bacteria and Archaea) or by ATP-driven bending of a membrane-bounded 9+2 microtubule axoneme (Eukarya); the three domain-level machines are functionally analogous but not homologous.
It can be Identify and localise an appendage using imaging and type-appropriate structural or molecular evidence.; Measure its dimensions, attachment continuity and movement under recorded conditions.; Track assembly, shortening, damage, detachment or recovery across observations.; Relate appendage movement to cell displacement or local fluid movement without assuming that correlation proves causation.; Assess a proposed mechanical, chemical or genetic perturbation against architectural identity, host context and available evidence.; Compare pre-intervention and post-intervention states with controls that distinguish flagellar effects from whole-cell effects..
Distinguishing features
Establish that the observed structure is a discrete appendage with evidence of cellular attachment or origin, rather than debris, a secreted fibre or a cell-body projection.
Test whether structural or molecular evidence supports a bacterial flagellum, a eukaryotic flagellum, or an archaeal appendage requiring an explicit flagellum-versus-archaellum naming decision.
Where motion is observable, distinguish rotation of a filament from bending waves along an appendage; do not infer architectural type from the word 'flagellum' alone.
Distinguish bacterial flagella from pili or fimbriae using attachment machinery, filament composition or validated markers; length and apparent motility alone are insufficient identification criteria.
For eukaryotic structures, record the organism-specific basis for calling an appendage a flagellum rather than a cilium; do not assume a universal distinction based on length or number.
Scope
+ Evidence identifying the appendage as a flagellum and distinguishing its architectural type
+ Flagellar structure, dimensions, continuity and attachment to the cell
+ Motion generation, observed movement and coupling to cellular behaviour
+ Assembly, maintenance, damage, detachment and recovery
+ Conditions and interventions affecting flagellar observation or function
- Whole-cell identity, viability and metabolism except as context for flagellar state
- Complete models of cilia, pili, fimbriae and other neighbouring appendages
- Whole-organism locomotion, development or disease
- Environmental fluid dynamics beyond local conditions affecting the appendage
- Complete gene-regulatory and protein-interaction networks
- Laboratory instrument operation and general experimental protocols
Characteristics
- Architectural identity
- bacterial flagellum | eukaryotic flagellum | archaeal naming boundary unresolved | other unresolved identification Determines which structural expectations, activity measurements and interventions are applicable.
- Host and attachment site
- host cell reference; attachment apparatus reference; position in a stated cellular coordinate frame Connects the appendage to its cellular context and distinguishes its movement from cell-body movement.
- Length and diameter
- µm or nm, with measurement method, uncertainty and contour-versus-projected length specified Supports identification and detection of growth, shortening or structural damage.
- Structural integrity
- apparently intact | incomplete | deformed | broken | detached | unresolved Separates visible structural defects from functional inactivity without a visible defect.
- Motion mode
- filament rotation | bending or beating | mixed apparent motion | no motion detected | unresolved Selects appropriate activity measurements and prevents conflating distinct mechanisms.
- Motion rate
- rotation frequency or beat frequency in Hz, with mode, observation interval and conditions Quantifies activity while preserving the distinction between rotation and beating.
- Shape during movement
- time-resolved centreline; curvature in µm⁻¹; applicable waveform amplitude and wavelength in µm Reveals changes in movement that a single frequency value would miss.
- Relationship to other flagella
- other appendage references; observed physical grouping or movement coordination; unresolved Allows an individual flagellum's behaviour to be interpreted within a multi-appendage system.
- Functional assessment
- activity demonstrated | activity reduced against stated reference | no activity detected | not assessed Prevents absence of observed motion from being treated automatically as irreversible failure.
Also called
Where this came from
wikidata · CC0 1.0
Also registered as vr.tr.flagellum
Drafted structure
Bundle to layer to finding to question, as the second pass will find it: 5 bundles · 9 layers · 16 findings · 24 questions.
Flagellar identity Evidence that the structure belongs to the registered thing and identification of its architectural type.
The name flagellum spans contexts in which structural expectations and movement mechanisms cannot be treated as interchangeable.
Appendage identification
Establishes the observed object's identity and cellular origin.
Identification evidence
Records observations supporting flagellar identity and plausible competing identifications.
- What imaging, structural or molecular evidence identifies this appendage as a flagellum? definition
- What evidence excludes a pilus, fimbria, cell-body projection or detached extracellular fibre? boundary
Architecture and naming
Resolves which biological meaning of flagellum applies.
Architectural assignment
Records the supported architectural class and any unresolved terminology boundary.
- Which structural features or validated markers support the proposed architectural type? definition
- Does the source terminology require clarification against cilium or archaellum, and what convention is being followed? boundary
Structure and cellular attachment The appendage's geometry, structural continuity and connection to its host cell.
Flagellar activity depends on a physical structure whose attachment and damage must be distinguishable from movement alone.
Filament geometry
Describes the observable appendage and type-appropriate internal organisation.
Dimensions and organisation
Records measured geometry and which structural components are resolved.
- What are the contour length, diameter and resting shape, with measurement uncertainty? measurement
- Which type-appropriate components, such as a filament, hook, membrane or axoneme, are directly resolved rather than inferred? provenance
Attachment and neighbours
Locates the flagellum on its cell and records interactions with other appendages.
Attachment continuity
Records the connection to the cell and the individual appendage's place within any flagellar arrangement.
- Where does the flagellum attach, and what evidence shows continuity with its attachment apparatus? measurement
- Can this flagellum be distinguished from neighbouring flagella throughout the observation, including when they form a moving group? boundary
Movement and functional coupling Observed flagellar movement and its relationship to cellular or local fluid behaviour.
A flagellum's presence, motion and functional contribution are separate assessments requiring different evidence.
Motion pattern
Characterises rotation, bending or apparent inactivity in an appropriate reference frame.
Resolved flagellar motion
Records the movement mode, rate and shape changes supported by the observation.
- Does the appendage rotate, propagate bending waves or show another apparent pattern after accounting for cell-body movement? measurement
- What rates, direction changes and waveform features are resolved at the recording's spatial and temporal resolution? measurement
Functional contribution
Connects appendage activity to an observed outcome and separates evidence from assumed function.
Activity-outcome coupling
Records evidence relating flagellar activity to displacement, fluid movement or another demonstrated role.
- What cell displacement, local fluid movement or other outcome accompanies this flagellum's activity? measurement
- What comparison or intervention supports attributing that outcome to this flagellum rather than other appendages or external forces? provenance
State transitions and intervention Changes in flagellar structure or activity and the evidence needed to choose and interpret interventions.
An agent must distinguish assembly, reversible inactivity and damage before deciding how to observe or alter the appendage.
Assembly, damage and recovery
Tracks structural and functional changes through time.
Flagellar state trajectory
Records whether a flagellum is forming, maintained, changing, damaged or recovering.
- What observations distinguish assembly or normal remodelling from breakage, loss or preparation artefacts? boundary
- How do length, attachment integrity and movement change over time, and is recovery observed? measurement
Perturbation and interpretation
Assesses proposed actions and the conditions needed to interpret their effects.
Type-appropriate intervention
Records an intervention's intended flagellar target, evidential basis and distinguishable outcomes.
- Which observation or perturbation is supported for this architectural type, host cell and intended outcome? action
- Which controls and local conditions are needed to distinguish a flagellar effect from altered host viability, energy availability, fluid resistance or surface attachment? action
Evidence and external alignment What the world already says about this thing, gathered so the model can be checked against it.
A model that cannot be lined up against existing standards, identifiers and practice cannot be adopted by anyone who already uses them.
Reported evidence
Findings from the breadth pass, kept separate from the structural claims.
Kinds and varieties
Reported by the breadth pass; each item needs checking against its source before it becomes normative.
- Bacterial flagellum (helical flagellin filament driven by a rotary basal motor, typically assembled by distal-tip growth)
- Sheathed bacterial flagellum (filament wrapped by an outer-membrane extension; typical of Vibrio and Helicobacter)
- Periplasmic flagellum / endoflagellum of spirochetes (filaments in the periplasm that produce corkscrew motility of the cell body)
- Archaellum (archaeal rotary filament homologous to type IV pili and assembled from the base, not to the bacterial flagellum)
- Eukaryotic motile flagellum (9+2 axoneme with dynein arms; the same organelle class as a motile cilium)
- Mammalian sperm flagellum (9+2 axoneme plus outer dense fibers and, in the principal piece, a fibrous sheath)
- Polar versus lateral bacterial flagellar systems (distinct motors/filaments used for swimming versus surface swarming in some Vibrionaceae)
- Protist flagella with extra-axonemal specializations (e.g. the paraflagellar rod of trypanosomes)
- Which of these kinds and varieties hold for the sense of flagellum this model covers, and on what evidence? provenance
Identifiers and schemes
Reported by the breadth pass; each item needs checking against its source before it becomes normative.
- MeSH - D005407 - Heading Flagella; covers prokaryotic and eukaryotic cellular flagella, not the insect antennal homonym.
- Gene Ontology - GO:0009288 - Cellular-component term bacterial-type flagellum.
- Gene Ontology - GO:0005929 - Cellular-component term cilium; eukaryotic flagella are annotated in this hierarchy rather than as a separate GO organelle.
- UniProt keyword - KW-0282 - Keyword Flagellum on proteins that are structural or functional components of a flagellum.
- Which of these identifiers and schemes hold for the sense of flagellum this model covers, and on what evidence? provenance
Standards and regulation
Reported by the breadth pass; each item needs checking against its source before it becomes normative.
- Kauffmann-White-Le Minor antigenic formulae, including H (flagellar) antigens - WHO Collaborating Centre for Reference and Research on Salmonella, Institut Pasteur
- ISO/TR 6579-3:2014 Microbiology of the food chain - Horizontal method for the detection, enumeration and serotyping of Salmonella - Part 3: Guidelines for serotyping of Salmonella spp. - International Organization for Standardization
- WHO laboratory manual for the examination and processing of human semen, 6th edition (2021) - World Health Organization (sperm motility as a clinical readout of flagellar function)
- European Respiratory Society guidelines for the diagnosis of primary ciliary dyskinesia - European Respiratory Society (axonemal/flagellar ultrastructure and beat in PCD)
- Which of these standards and regulation hold for the sense of flagellum this model covers, and on what evidence? provenance
Real-world use
Reported by the breadth pass; each item needs checking against its source before it becomes normative.
- Soft-agar swarm/swim plates and hanging-drop microscopy to score bacterial motility in clinical and food microbiology
- Salmonella serotyping by H (flagellar) antigens in public-health reference laboratories
- Sperm-motility assessment in fertility clinics as a direct readout of flagellar beating
- Pathogenesis and innate immunity: flagellin is a TLR5 ligand, and flagella aid colonization or invasion in Salmonella, Pseudomonas, Helicobacter and others
- Structural biology and nanomotor engineering of the bacterial rotary motor
- Diagnostic electron microscopy of sperm tails and respiratory cilia for ultrastructural flagellar/ciliary defects
- Which of these real-world use hold for the sense of flagellum this model covers, and on what evidence? provenance
Typical measurements
Reported by the breadth pass; each item needs checking against its source before it becomes normative.
- Bacterial filament length - 5-20 - µm
- Bacterial filament diameter - ~20 - nm
- Eukaryotic flagellum diameter - 0.20-0.30 - µm
- Human sperm flagellum length - 45-55 - µm
- Bacterial motor rotation rate - 100-300 (some species >1000) - Hz
- Escherichia coli free-swimming speed - 20-40 - µm/s
- Human sperm beat frequency - 10-25 - Hz
- Bacterial flagellar-motor torque - 1000-4000 - pN·nm
- Which of these typical measurements hold for the sense of flagellum this model covers, and on what evidence? provenance
Failure modes and hazards
Reported by the breadth pass; each item needs checking against its source before it becomes normative.
- Loss-of-function mutations in motor, hook or filament genes abolish swimming and can reduce colonization or virulence where motility is required
- Phase variation of flagellin (e.g. Salmonella FliC/FljB) switches H antigen and evades antibody
- Shed flagellin activates TLR5 and can drive mucosal inflammation
- Primary ciliary dyskinesia (including Kartagener syndrome): defective dynein arms yield immotile axonemes, with bronchiectasis, laterality defects and male infertility
- Asthenozoospermia from ultrastructural defects of the sperm flagellum
- Mechanical shearing in high-shear culture strips bacterial filaments and yields false motility-negative phenotypes
- Motility-agar false negatives from wrong agar concentration, temperature or phase-off Salmonella
- Which of these failure modes and hazards hold for the sense of flagellum this model covers, and on what evidence? provenance
Regional variation
Reported by the breadth pass; each item needs checking against its source before it becomes normative.
- Cell-biology usage treats the eukaryotic cilium and flagellum as one organelle; zoological usage still splits them by number and relative length
- Archaellum (name proposed 2012) is standard in archaeal microbiology, while many general textbooks still say archaeal flagellum
- CDC and WHO/Pasteur Salmonella serovar aliases have differed historically for some H-antigen formulae
- Clinic language for the sperm organelle varies (flagellum, sperm tail, flagellum spermatozoi) by medical tradition and language
- East Asian technical literature uses 鞭毛 for the cellular organelle; the insect antennal sense is usually separated as flagellomeres/鞭节
- Which of these regional variation hold for the sense of flagellum this model covers, and on what evidence? provenance
Neighbouring kinds and how to tell them apart
Reported by the breadth pass; each item needs checking against its source before it becomes normative.
- Cilium (motile) - Same 9+2 axoneme as a eukaryotic flagellum; no ultrastructural test separates them - the split is conventional (few and long versus many and short).
- Primary (non-motile) cilium - Usually 9+0, lacks motile dynein arms, and functions in sensing rather than propulsion.
- Type IV pilus - Thinner filament used for twitching, attachment or DNA uptake by extension/retraction, not rotary helical propulsion; related to the archaellum, not to the bacterial flagellum.
- Type III secretion injectisome - Homologous to the bacterial flagellar basal body but translocates effectors and has no motility filament.
- Fimbria / common pilus - Short, numerous adhesin filaments with no rotary motor and no flagellin.
- Stereocilium - Actin-core projection on sensory hair cells, not a tubulin axoneme.
- Axoneme - The 9+2 microtubule core of a eukaryotic flagellum, not the whole organelle (membrane plus accessory structures).
- Insect antennal flagellum - Homonym: the distal cuticular region of an arthropod antenna made of flagellomeres, not a cellular motility filament.
- Which of these neighbouring kinds and how to tell them apart hold for the sense of flagellum this model covers, and on what evidence? provenance
Sources
- The Rotary Motor of Bacterial Flagella (Annual Reviews, Annual Review of Biochemistry, 2003) - Bacterial flagellum structure, rotary motor mechanism, filament dimensions, rotation rates, and torque.
- The archaellum: an old motility structure with a new name (Elsevier, Trends in Microbiology, 2012) - That archaeal flagella are not homologous to bacterial flagella, the name archaellum, and the type-IV-pilus relationship.
- Molecular Biology of the Cell, 6th edition (Garland Science, 2014) - Eukaryotic axoneme (9+2) architecture, dynein-driven bending, and the conventional cilium/flagellum identity.
- Antigenic Formulae of the Salmonella Serovars, 9th edition (WHO Collaborating Centre for Reference and Research on Salmonella, Institut Pasteur, 2007) - Flagellar (H) antigens as a formal identifier in Salmonella serotyping (Kauffmann-White-Le Minor).
- WHO laboratory manual for the examination and processing of human semen, 6th edition (World Health Organization, 2021) - Clinical measurement of sperm motility as a real-world assay of eukaryotic flagellar function.
What the second pass must settle
- Does this registry entry include archaeal archaella under historical flagellum terminology, or should it relate to a separate registered concept?
- How should this registry divide or connect eukaryotic flagella and cilia when terminology does not establish a universal structural boundary?
- Which architectural components and identification markers should be required for each supported lineage, and which remain optional or unresolved?
- What reference conditions and measurement limits are needed to distinguish reduced activity, reversible inactivity and structural failure in each supported context?
- Which non-propulsive roles and intervention responses have sufficient organism-specific evidence to include in a researched publication?